1. Technical Field
The present invention relates to projectors.
2. Related Art
A projector using a discharge lamp such as a high-pressure mercury lamp or a metal halide lamp has been put to practical use. As such a projector, in JP-A-2003-102030, for example, a projector having a unit for varying the intensity of a light source in accordance with a color separation unit or the like in synchronization with a picture signal is disclosed. However, JP-A-2009-237302 describes that if the intensity of the light source is simply varied, an electrode of the discharge lamp will wear out significantly.
Moreover, in recent years, a projector that outputs a stereoscopic picture by using a discharge lamp such as a high-pressure mercury lamp or a metal halide lamp has been put to practical use.
One of the methods to output a stereoscopic picture is a method by which switching between a picture for the right eye and a picture for the left eye is performed and the picture for the right eye and the picture for the left eye are alternately output (for example, active shutter glasses technology such as “XPAND beyond cinema” (a trademark of X6D Limited)). In this method, the right eye is made to view the picture for the right eye and the left eye is made to view the picture for the left eye by using active shutter glasses etc. synchronized with a picture signal, whereby the picture is made to appear stereoscopically by using parallax between what the right and left eyes see.
When a stereoscopic picture is projected by the method by which a picture for the right eye and a picture for the left eye are alternately output, the amount of light that enters the right eye and the left eye is less than half of the amount of light that enters the right eye and the left eye when an existing two-dimensional picture is projected. Moreover, when crosstalk by which the picture for the right eye enters the left eye or the picture for the left eye enters the right eye occurs, the observer loses the sense of viewing the stereoscopic picture. Therefore, it is necessary to provide a period in which both active shutters are closed. As a result, when a stereoscopic picture is projected by the method by which a picture for the right eye and a picture for the left eye are alternately output, the picture appears darker than when an existing two-dimensional picture is projected. To make the picture appear bright, the drive power can be simply increased. However, this increases the power consumption of the projector or accelerates the deterioration of peripheral parts associated with the increase in drive power.
Moreover, if control to reduce the brightness of the discharge lamp in a period in which both active shutters are closed and increase the brightness of the discharge lamp in a period in which one of the active shutters is opened is performed to make the picture appear bright, the temperature of the electrode of the discharge lamp is reduced in a period in which the brightness of the discharge lamp is reduced, resulting in insufficient fusibility of the tip of the electrode. This may cause deformation of the electrode. When the electrode is deformed, there is a possibility of, for example, the occurrence of flicker. Therefore, special consideration is needed to prevent deformation of the electrode.